The longevity of aircraft, particularly aircraft used in commercial aviation, usually far exceeds changes in the level and capabilities of on board equipment used to assist the flight crew in controlling the aircraft. Thus, the aircraft manufacturer, or the customer, such as a commercial airline, in their desire to upgrade their equipment with the latest technology, such as regarding on board flight management systems (“FMS”) is faced with considerable expense, and downtime, in attempting to upgrade the existing aircraft with the latest technology. In many instances, particularly regarding commercial aviation, this may not be a mere matter of competitive choice but may be mandated by a regulatory agency, such as the Federal Aviation Administration. In the case of commercial fleets involving substantial numbers of aircraft this can be quite costly and time consuming, but necessary as the cost of the aircraft involved, and the time to construct them, leaves very little choice but to retrofit the existing fleet.
One such area where there have been considerable changes which improve the capability and efficiency of the aircraft is in the area of flight management systems which have now needed to be updated to keep up not only with competitive pressures, but with the latest capabilities and functionality desired by the FAA as well. A typical example of this is with respect to the preexisting flight management system on board a typical conventional MD-80/90 aircraft which is a work horse of many airline fleets and has been utilized by the airlines for many years. Such aircraft, despite their long use, still have many flying hours left but need the preexisting on board flight management system to be replaced or upgraded to keep up with modern needs and requirements. These preexisting systems, such as the preexisting flight management system on board a typical MD-80/90 aircraft, which were satisfactory when they were originally installed on board the aircraft, and have previously been for several years thereafter, generally have a legacy EFIS system which, in today's environment, results in various existing system shortcomings, such as providing limited FMS Navigation database storage capacity, lacking a desired required time of arrival or RTA capability, and lacking the ability to provide RNP VNAV, LPV and RNAV capability utilizing a GPS or global positioning system based navigation solution or the ability to control the autopilot and auto-throttle functions during different phases of flight such as Instrument Landing System approach and also provide the ability to optimize these functions through constant monitoring of the aircraft's flight parameters.
Prior art efforts in this area, in order to meet these and other current needs in preexisting aircraft still having considerable life, have involved the often costly and inefficient complete replacement of the preexisting flight management system with an entirely new system. This was the typical approach previously utilized rather than attempting to take advantage of various key legacy components in a retrofitted system, such as by overcoming these preexisting system shortcomings by replacing the legacy EFIS system with other components while optimizing the usage of preexisting legacy components from the prior on board flight management system, such as the legacy advance flight management computer or AFMC which in the navigation solution utilized on preexisting aircraft, such as the MD-80/90, relies on a single AFMC to calculate such parameters as lateral guidance, vertical guidance, and performance calculations. Thus, it would be desirable in any navigation upgrade solution for preexisting aircraft to be able to retain the legacy AFMC in any upgraded navigation solution for that aircraft, rather than replace the preexisting FMS system completely so as to be able, inter alia, to exploit the previously proven performance capabilities of the on board AFMC. In addition, because these preexisting flight management systems were not originally intended to utilize the type of GPS based navigation solutions preferred today, they did not have the capability of utilizing a GPS based navigation solution, such as to provide RNP, VNAV, LPV and RNAV capability.
Accordingly, a need or potential for benefit exists for viable upgraded flight management systems that can take advantage of and retrofit or cannibalize preexisting on board FMS system components, including the on board AFMC, in order to efficiently and cost effectively upgrade the capabilities of the preexisting FMS system to at least include improved GPS-based navigation and autopilot/auto-throttle functionality without having to completely replace it.